9/6 means full house pays 9, flush pays 6: that’s the good Jacks or Better (99.54% with perfect play). Check the paytable before you sit; 8/5 drops to 97.3%. Full-pay Deuces Wild returns 100.76% with perfect play, but it’s rare; most machines are “Not So Ugly” or worse.
Grading is exact: every one of the 32 ways to hold is checked against every possible draw.